Pneumatic relay



Dec. 3, 1968 L TAYLOR 3,413,997

PNEUMATIC RELAY Filed Dec. 20, 1965 2 Sheets-Shem 1 qji izi? INVENTOR BY TJOHN L. TAYLOI? Lil g 6M Dec. 3, 1968 J. L TAYLOR PNEUMATIC RELAY 2 Sheets-Sheet 2 Filed Dec. 20, 1965 INVENTOD JOHN L. TAYLOR 4, W 9

United States Patent 3,413,997 PNEUMATIC RELAY John L. Taylor, Marshalltown, Iowa, assignor to Fisher Governor Company, a corporation of Iowa Filed Dec. 20, 1965, Ser. No. 515,109 3 Claims. (Cl. 137-85) ABSTRACT OF THE DISCLOSURE A pneumatic relay convertible between snap-active service and throttling service by means of an ad ustable switching block on the relay housing.

This invention relates to pneumatic relays and, more particularly, to an improved pneumatic relay capable of either snap-acting service or throttling service without modifying the internal components of the relay.

In some applications for pneumatic relays, the installer might not know whether to use a snapacting device or a throttling device until he is on the job site. Thus, it might be necessary to carry both types. Further, in certain applications, for example oil well control, a different type relay may be required, dependent upon the fluid flow. At start up of the well, slime may flow and a snap-acting valve would be necessary. Later, when clear fluid flows, a throttling valve could be used. Heretofore, it was necessary to substitute a throttling relay for a snapacting relay to accommodate varying flow conditions.

One object of the present invention is to provide an improved pneumatic relay that may be readily adapted for either snap-acting service or throttling service by controlling the supply of air to and from the relay and without internal structural change in the relay.

A second object of this invention is to provide an improved pneumatic relay that can be readily converted from snap-acting service to throttling service without additional parts and by means of a simple external adjustment.

Another object of the present invention is to provide an improved snap-acting pneumatic relay provided with a pair of diaphragms constructed and arranged to be acted upon by equal and opposite forces to neutralize the elfect of supply pressure on the pair of diaphragms and a control diaphragm of larger effective area than either one of said pair of diaphragms, the diaphragms being interconnected by spacer means for movement together. Other objects and advantages of this invention will become more apparent hereafter.

The present invention will be more fully understood when the following specification is read in conjunction with the accompanying drawing, wherein:

FIG. 1 is an elevation in section of a pneumatic relay embodying the principles of the present invention, with such relay being adapted for snap-acting service;

FIG. 2 is a detail view of the relay case with part of the pneumatic relay being omitted to show the switching block for controlling the flow passages to adapt the relay for either throttling or snap-acting service, the switching block being shown in position for snap-acting service;

FIG. 3 is a side view of a part of the pneumatic relay rotated 90 degrees with respect to FIG. 1 and illustrating the location of the inlet opening and the exhaust passage from the case;

FIG. 4 is a view of the pneumatic relay block taken generally along line 4--4 of FIG. 2;

FIG. 5 is an enlarged rear view of the switching block illustrating the recesses therein;

FIG. 6 is an elevation in section of a pneumatic relay embodying the principles of the present invention, with the relay being adapted for throttling service;

FIG. 7 is a plan view of the relay case with parts omitted, illustrating the position of the switching block for throttling service;

FIG. 8 is a side view of the switching block taken along line 8-8 of FIG. 5; and

FIG. 9 is a side view of the switching block taken along line 9-9 of FIG. 5.

Referring now to FIG. 1, there is illustrated the relay means of the present invention as adapted for snap-acting service, such relay means comprising a relay 10 carried in a conventional manner on the relay case 12. Provided in the case or block 12 is an inlet port 14 adapted to be connected to a source of supply pressure.

Sealingly engaged 'with the opening or bore 16 in the case 12 is a nozzle assembly 18 comprising a tubular member 19 having a threaded end engaged with the opening 16 in the case 12 and a nozzle portion 20 threadedly engaged with the member 19 and having an opening 21 adjacent the outer end thereof. Supply air entering the inlet port 14 will flow through the passages 22, 23 and 24 to the nozzle assembly 18. Such air will pass through the fixed restriction 26 in the member 19 and through the passage 27 in the nozzle assembly and exit from the nozzle assembly through the nozzle opening 21.

Movably disposed adjacent to the nozzle assembly 18 is a shoe member 28, which is movable toward and away from the nozzle opening 21 to control the bleed of air therethrough in response to a predetermined condition. For example, the shoe member 28 may be carried on a rod 29 suitably pivoted in response to the position of a float member in a liquid level control. The shoe may include an adjustable stop 28a adapted to cooperate with nozzle opening 21 for controlling the flow of air there through.

The nozzle member 20 is threadedly engaged with the member 19 to provide for adjustment of the nozzle opening 21 with respect to the shoe 28 in order to adjust the output range of the relay. The spring 30 functions to maintain the members 19 and 20 in desired adjusted re lationship with respect to one another. Resilient O-ring seal means 31 are provided between the members 19 and 20 to prevent undesired loss of fluid pressure from the passage 27 to the atmosphere between the members 19 and 20.

The relay housing is comprised of a base 34, intermediate plates 35 and 36, and end plate 37 secured together in a well known manner. The edge of flexible diaphragm 38 is sealed between the base portion 34 and the intermediate plate 35. The diaphragm 39 is sealed between the intermediate plates 35 and 36. Diaphragm 40 is sealed between the plate 36 and the end cap 37. Spacer means 41 interconnect the diaphragms 38, 39 and 40 for simultaneous rnovement.

The diaphragms 38, 39 and 40 divide the interior of the relay housing into separate compartments 42, 43, 44 and 45. The compartment 43 communicates with the inlet port 14 in the base or case 12 via passages 22, 23, 46, 48, 50, 52 and 54 and opening 38' in diaphragm 38. The spacer means 41 includes a central tubular member 56 having a passage 57 therethrough that communicates with the pressure in compartment 43 via openings 58 extending the exhaust port 64. The valves are interconnected by valve stem 67 for simultaneous operation. The spring 70 provided concentrically about the valve means acts at one end upon the partition 62 and at the other end upon the spacer means 41 to move the spacer means away from the inlet valve 66 to open the inlet port 60. Spring 74 acts between the support plate 76 afiixed within the base portion by screw means 77 and the flange end portion of the exhaust valve 68 to bias the exhaust valve toward closed position.

Provided within the base portion 34 below the exhaust valve 68 is a chamber 80 which is adapted to be connected to the atmosphere via passages 81 and 83, as will be more fully explained hereafter. The compartment 44 defined between the diaphragms 39 and 40 is vented to the atmosphere via a vent opening 84 in the plate member 36.

Extending from the chamber 42 is an internal passage in the base portion 34, which passage 86 is adapted to be connected via port 87 with a suitable pneumatic control element, as for example, a control valve.

Air is supplied to the chamber 45 defined between the diaphragm 40 and the end plate 37 from the inlet port 14 via passages 22, 23, 24, restriction 26, passage 88, plug member 89, passages 90 and 90 in the base portion 34, and passages 91, 92 and 93 defined in the intermediate plates 35 and 36 and the end plate 37, respectively. Plug member 89 carries an O-ring to seal passages 90, 90' from chamber 80.

Resilient O-ring seal means are provided to seal the passages communicating between the base portion 34 and the case 12. O-ring 95 is disposed about the passage 52, O-ring 96 is disposed about the chamber 80 and O-ring 97 is disposed about the passage 90.

Referring to FIGS. 2, 3, 4 and 5, there is seen the orientation of the passages in case 12 to permit exhaust of fluid pressure from the case and also the means for converting the pneumatic relay between snap-acting service and throttling service. In FIG. 2, the relay has been omitted to show the case 12 more clearly. There is provided in the case 12 passages 52, 23, 81, 88 and 86. Extending from the passages 52, 23 and 81 in the case 12 are transverse passages 50, 46 and 83. The transverse passages 50, 46 and 83'open to a side of the case 12 (see FIG. 4). Cooperating with the side of the case 12 is a switching block 110 that is adapted to selectively connect either passages 46 and 50 or 46 and 83 to adapt the pneumatic relay for snap-acting service and throttling service, respectively. In FIG.- 2, the switching block is positioned to adapt the relay for snap-acting use.

As seen in FIGS. 3 and 4, there is provided in case 12 exhaust passage means comprising an exhaust passage 82 opening to the side of case 12 adjacent the outlets from passages 50, 46 and 83 and a transverse exhaust passage 82a communicating at one end with passage 82 and at the other end with the atmosphere.

Considering FIG. 2, the switching block 110 is afiixed to the case 12 by suitable fastening means, as for example, machine screws 111, in such manner that the elongated recess 112 therein is adapted to communicate the passage 50 with the passage 46 so as to define connecting passage 48. The semicircular exhaust recess 103 (FIG. in the switching block 110 is adapted to communicate the passage 83 with the exhaust passage means so as to vent the passage 83 to atmosphere.

FIG. 5 is a rear view of switching block 110 showing the elongated recess 112 therein for communicating passage 46 with either passage 50 or passage 83 and illustrating the semi-circular exhaust recess 103 for selectively communicating either passage 83 or 50 to exhaust passage means 82, 82a. Machine screws 111 pass through the openings 115 for securing the switching block to case 12.

Considering now the operation of the relay in snapacting service, supply pressure is supplied to the inlet port 14 and passes through the passages 22, 23, 46, 48, 50, 52 and 54 to the chamber 43. With supply pressure in chamer 43, the forces across the diaphragms 38 and 39 are equal and opposite.

When the shoe 28 is away from the nozzle opening 21, the relay spring 74 biases the exhaust valve 68 to the closed position and the relay spring biases the spacer means 41 away from the eonically shaped inlet valve 66 to open inlet port 60. Thus, supply pressure will pass from the chamber 43 to the chamber 42 through ports 58 and 60 and through the passage 86 and port 87 to the control valve. With pressure in chamber 42, the force from the diaphragm 38 is reduced, thus insuring that the supply port 60 will remain open to allow full supply pressure to build up in chamber 42.

As the shoe 28 moves toward the nozzle assembly 18, the nozzle opening 21 is restricted. Restriction of the nozzle opening will cause pressure build up between the nozzle opening 21 and the fixed restriction 26. The closer the shoe 28 moves to the nozzle opening 21, the higher the nozzle pressure will build up. The increased pressure will pass through the passageways 88, 90, 91, 92 and 93 to the chamber 45. When the force across the diaphragm 40 is greater than the force across the diaphragm 39 and the force from the relay spring 70, the diaphragm assembly moves downward as viewed in FIG. 1, closing the inlet port 60.

There will be no pressure change in the chamber 42 until the exhaust port 64 starts to open and then pressure in the chamber 42 will bleed through the exhaust port to the exhaust chamber 80. The pressure bleeding through the exhaust port 64 will cause a force across the diaphragm 38 which increases the opening of the exhaust port 64. Since this action is independent of any change in nozzle pressure and is self-perpetuating, it will continue until the exhaust port is wide open and the pressure in chamber 42 is atmospheric.

When the exhaust port 64 is open, the output pressure acting on the diaphragm of the control valve passes through the passage 86 to the chamber 42 through the exhaust port 64 to the chamber and through the passages 81 and 83, recess 103 and exhaust passages 82 and 82a to the atmosphere.

When the shoe 28 moves away from the nozzle opening 21, the nozzle pressure in chamber 45 bleeds out through the passages 93, 92, 91, and 88 and the nozzle opening 21 faster than supply pressure can enter through the fixed orifice 26. This will reduce the force across the diaphragm 40 until it is less than the force from the spring 70. It is noted that the force across the diaphragm 39 is equal and opposite to the force across the diaphragm 38. Thus, when the effective force acting upon the spacer means 41 urging it downwardly as viewed in FIG. 1 is less than the force from the relay spring 70, the diaphragm assembly will move upwardly as viewed in FIG. 1 and permit closure of the exhaust port 64. There will be no pressure in the chamber 42 until the inlet port 60 starts to open and bleeds pressure into chamber 42. The pressure bleeding into chamber 42 reduces the force across the diaphragm 38 which increases the opening of the inlet port 60. This action is independent of any change in nozzle pressure and is self-perpetuating. The action will continue until inlet port 60 is wide open and full supply pressure is in chamber 42.

Referring now to FIGS. 6 and 7, there is illustrated the relay mechanism of the present invention adapted for throttling service. As aforenoted, one feature of the present invention is that the pneumatic relay may be adapted for either throttling service or snap-acting service without change of any of the internal components only a simple external reorientation of a switching block 110. Accordingly, the same elements in FIGS. 6 and 7 are identified by the same numeral as used in FIGS. 1 and 2. It is seen that the only difference between the relays in FIGS. 1 and 2 and FIGS. 6 and 7, respectively, is the arrangement of the passages in the case 12.

With the pneumatic relay adapted for throttling service, as shown in FIGS. 6 and 7, supply pressure enters through the supply port 14 and passes through internal passages 22 and 23 in case 12 and through passages 46 and 102 to the chamber 80. The valve member 68 functions as an inlet valve to restrict the passage of fluid from the compartment 80 to the compartment 42 through the port 64 in the partition 62. Fluid will also pass through the passage 24, restriction 26, and passage 27 to the nozzle opening 21. When the shoe 28 moves toward the nozzle assembly 18, the nozzle opening21 is restricted. This allows nozzle pressure to build up within the nozzle assembly between the nozzle opening '21 and the fixed restriction or orifice 26. The closer that the shoe 28 moves to nozzle opening 21, the higher the nozzle pressure will build up. The nozzle pressure will pass through the passage 88 in block 12, passage 90 in base 34, and passages 91, 92 and 93 to the chamber 45. When the force across the diaphragm 40 is greater than the force across the valve 68 plus the force from the relay springs 70 and 74, the diaphragm assembly will move downwardly as viewed in FIG. 6 to close the exhaust port 60 defined at the end of the tubular central portion 56 of the spacer means 41.

At this point, the valve 68 is in a neutral position, that is, both the supply port 64 and the exhaust port 60 are closed.

As the diaphragm assembly continues to move downwardly, the supply port 64 is opened and supply pressure can enter the chamber 42 and pass through passage 86 and port 87 to the diaphragm of a control valve (not shown). With supply port 64 open, pressure builds up in chamber 42. When the force across the diaphragm 38, along with the combined force from the relay springs 70 and 74, is greater than the force across diaphragm 40, the diaphragm assembly moves upwardly, as viewed in FIG. 6, until valve member 68 abuts partition plate 62 to close the supply port 64. Once again, the valve 68 is in a neutral position. For each nozzle pressure in chamber 45, as determined by a given position of the shoe 28, there is one and only one pressure in chamber that i will cause the valve 68 to stay in a neutral position. When either port 60 or port 64 is open, the forces across the diaphragms 40 and 38 are not in balance.

The chamber 44 is vented to the atmosphere through the vent passage 84. The chamber 43 may be vented to the atmosphere through passages 54, 52, 50, the recess 103 in switching block 110 and exhaust passage means 82, 82a in case 12. The atmospheric venting of the chambers 43 and 44 balances the fluid forces acting directly on diaphragm 39.

When the shoe 28 moves away from the nozzle opening 21, the nozzle pressure in the chamber 45 bleeds out through the passages defined by passages 93, 92, 91, 90 and 88 and the nozzle opening 21 faster than supply pressure can enter through the fixed orifice 26. This will reduce the force across the diaphragm 40 until it is less than the force across the diaphragm 38 plus the forces from the relay springs 70 and 74. Thus, the diaphragm assembly will move upwardly, as viewed in FIG. 6. Up ward movement of the diaphragm assembly will close the supply port 64 and open the exhaust port 60. The output pressure acting on the diaphragm of the control valve will then pass through port 87 and passage 86 to chamber 42. The outputpressure will pass from the chamber 42 to the atmosphere through the exhaust port 60, passage 58, chamber '43, passages 54, 52, 50, recess 103 in switching block 110 and exhaust passage means 82, 82a.

Referring now to FIG. 7, it is seen that the recess 112 in the switching block cooperates with the passages 46 and 83 to define the passage 102. The transverse passage '50 communicates with the exhaust recess 103 provided in the switching block to vent the passage to atmosphere through exhaust passage means 82, 82a.

Means are provided on the switching block to indicate to the user whether the relay is adapted for throttling service or for snap-acting service. As seen in FIGS. 2, 5, 8 and 9, such means comprise indicia plate 113 having indicia tabs 116 and 117 that are olfset perpendicularly from the plane of the plate 113. The plate conforms generally to the configuration of the block Tab 116 has the indicia T, or similar indicia, thereon and tab 117 has the indicia S, or similiar indicia, thereon. When the block 110 is positioned for snap-acting service, with the plate 113 in position on block 110, tab 117 and the indicia S will be visible. When the block 110 is positioned for throttling service, tab 116 and the indicia T will be visible.

There has been provided by this invention a novel switching arrangement to permit conversion of a pneumatic relay between throttling service and snap-acting service without change of internal parts and without removing the relay from the line. By the improved con struction of the present invention, the inventory of components and devices may be materially reduced, for a single relay can be readily adapted for either snap-acting service of throttling service. The pneumatic relay of the present invention will function in a reliable manner whether used as a snap-acting device or as a throttling device.

While there has been shown and described a particular embodiment of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention and, therefore, it is intended in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new, and desire to secure by Letters Patent of the United States, is:

1. A pneumatic relay capable of conversion for both snap-acting service and for throttling service comprising housing means, said housing means having an inlet adapted to communicate with a source of fluid operating pressure, a diaphragm assembly including three diaphragms defining first, second, third and fourth spaced chambers within said housing means, said diaphragms being operatively connected by spacer means for conjoint operation, :a Ibleed nozzle assembly on said housing means, supply passage means in said housing for supplying said operating pressure from said inlet to :said bleed nozzle assembly, a passageway communicating said first chamber with said bleed nozzle assembly, said bleed nozzle assembly controlling pressure in said first chamber, a passageway in the spacer means communicating said third and fourth chambers, first, second and third passages opening to the exterior of the housing means adjacent one another and said first and third passages being adapted to communicate with said second passage, said second passage communicating with supply passage means, exhaust passage means in said housing means having an opening at the exterior of the housing means adjacent said 0penings from the said first, second and third passages and communicating to the atmosphere, the fourth chamber being provided with an inlet port and exhaust port, the inlet port communicating with said third chamber, cooperating valve means responsive to movement of said diaphragm assembly for controlling flow through said inlet port and said exhaust port, said first passage communicating with said third chamber, said second passage communicating with said supply passage means and said third passage communicating with said fourth chamber, an outlet passage in the housing means for communicating the fourth chamber at a location remote from the inlet and exhaust port between the inlet and exhaust ports with a device to be operated, and switching means mounted externally on said housing means having a first position for selectively communicating the first and second of said three passages to one another for the snap-acting mode of relay operation, with the third passage being communicated to said exhaust passage means, and having a second position for selectively communicating the second and third passages to one another for the throttling mode of relay operation, with the first passage being communicated to said exhaust passage means, said switching means movable between first and second positions without interfering with the components within the housing means, said switching means comprising a switching block affixed externally to the housing means, said switching block having a first recess therein for selectively communicating only the first and second, or the second and third passages and a second recess for communicating the third or first passage respectively to the exhaust passage means, and means for detachably joining the switching block to the housing means, the first and second recesses being in the same side of the switching block.

2. A pneumatic relay as in claim 1 wherein said first, second, and third passage openings are aligned with one another and said exhaust passage opening adjacent said first, second, and third openings is offset from a line extending through the axes of said first, second and third 8 openings, said second recess in said switching block being semicircular, whereby the relay may be changed between snap-acting service and throttling service by moving the switching block from said first position to said second position.

3. A pneumatic relay as in claim 1 wherein indicia tabs extend from the switching block, the tabs bearing different indicia to clearly indicate to the user whether the relay is adapted for snap-acting service or throttling service.

References Cited UNITED STATES PATENTS Hunt a 137-270 ALAN COHAN, Primary Examiner. v 

